It is always pleasant and only becomes unpleasant if you allow it. If folks cant sit and eat and talk and find common ground, then God help us.
We can appear at a table as strangers, but we can leave it X days later as friends or with respect for each other. That's the positive spin, and in my experience it wins time after time and is the experience of most cruisers.
But if its really bad and you feel you dont fit with this table,,,then in ask to be moved, but dont go back to just doing your own thing in bufffet etc, keep in the social dining experience. I have met, laughed and cried with people I would never have met in my life if I had not dined at a table in the ships dining room